Fire Weather Index script

[HansR]

The link is : http://meteo.montagne-vert.nl/wxFWI.php (provisional page)

The area is agricultural in the valleys surrounded by hills either forested or with scrub. In the north and south the forested areas are larger. In summer it is extremely dry and the scrub value would be understood. But now all values should be low (I think). I'll experiment a bit.

grts Hans

[BCJKiwi]

I see your SFDC has dropped right away - what exactly did you change? Do you think you might have overdone it or have you just had a lot of rain and no wind?

I see you have removed the local conditions columns (temp/hum/wind/rain) so I need to ask the question to understand the rapid change.

[HansR]

Yes, the SFDC changes quickly and in big numbers. I did not change anything so far from my original settings. It is after this afternoons calculation I changed the scrub (isn't it shrub btw?) setting in slope from 15° to 5°. No other changes made but that should not be visible yet.

The temp/hum/wind/rain have been removed to fit the table and because they are displayed in graph below. I may change this in future but for now it fits. If you need them in the table for easy reading I can add them of course. Just ask.

[sfws]

I changed the scrub (isn't it shrub btw?)

Shrub= one small tree-like plant
Scrub = a type of landscape characterised by stunted (forest) growth - typically exposed to high winds, sea spray or poor soils

[HansR]

Thanks, I learned something!
In the region where I live there is scrub, but shrub is more extensive and prone to burning.
I do not think it will change my settings much.

[HansR]

Just saw the calculation for today. TheSFDC jumps from 369 (moderate, yesterday) to 4133 (extreme, today).
I do not understand the volatility of this calculated value given the weather situation.
Any suggestions?

[BCJKiwi]

Well it's not really for me to say (but I'll give it a shot).
This is Graeme's description of SFDC

SFDC (Scrub Fire Danger Code)
Based on predicted generated "fire intensity (kw/m2)" in flammable scrub type vegetation (tea tree, broom, gorse, manuka. This code denotes how difficult it would be to control a fire in this vegetation type should one start.

Tea Tree and Manuka are NZ terms for natives. They can grow up to 3 or 4 metres high when fully grown. They have light vegetation on top, are quite open below and shed a lot of fine fuel onto the ground.
Have attached a picture of a scrub fire that ocurred here in suburban Auckland a few days ago. As noted above, once a fire gets started (which is very easy in this type of vegetation) it spreads very rapidly, drying out the scrub in front of the flame front making it difficult to control. It is this behaviour that the index attempts to indicate.

[HansR]

OK, Thanks.
I just had a private communication with Graeme and his answer was roughly the same.
I think two things :

1) the xFDC codes are used to estimate ...how difficult it would be to control a fire in this vegetation type should one start.... So these codes have nothing to do with the fire staring risk assessment but with a control assessment in case we have a fire.

2) as the SFDC code seems to be very volatile I am beginning to think this is not valid for the area I live in. So I may drop the whole code from my site and simply ignore it. Scrub exists here but I think it is not half as explosive as it is in NZ because of other species, other soil, moisture content etc... As no specification exists the value of the code is NULL.

Valuable discussion for me.
Thank you @all.

[BCJKiwi]

You can just turn off all the reporting of scrub related (and any other) indices to the website and keep the rest.

[HansR]

You can just turn off all the reporting of scrub related (and any other) indices

I just did...